Electric incandescent lamp



July 29, 1958 A. s. VAUSE 2,845,569

' ELECTRIC INCANDESCENT LAMP Filed March 2, 1954 Inventor: 7 Arthur Samuel Vause,

His Attorney atent Ofifice 2,845,569 Patented July 29, 1958 2,845,569 ELECTRIC IN CANDESCENT LAMP Arthur S. Vause, Leicester, England, assignor to General Electric Company, a corporation of New York Application March 2, 1954, Serial No. 413,674 Claims priority, application Great Britain March 3, 1953 4 Claims. (Cl. 313-474 This invention relates to electric lamps having incandescent filaments, and more particularly to the smaller types of such lamps for use on automobiles, bicycles, hand flashlights or lanterns, in which it may be desirable that the filament should occupy a definite position with respect to the lamp base.

Electric lamps for automobiles, bicycles and hand flashlights, when in use, are liable to be subjected to severe vibration and shaking which may cause displacement of the filament. This is particularly objectionable in cases where the lamps are to be used with parabolic reflectors or lenses. Moreover, such vibrations and shocks tend to shorten the life of the lamp by causing fractures of the filament particularly at the joints between the filament and the leading-in wires.

In electric lamps of the type referred to, it has been proposed to obviate these disadvantages by extending one of the leading-in wires beyond the filament joint, so that it'engages with the interior of a tip formed in the bulb. This construction, however, is subject to the disadvantage that as the filament is supported at one end and not at the other, the two ends vibrate at different frequencies.

It is an object of my invention, therefore, to provide an electric incandescent lamp of the above-described general type having a filament-supporting structure which will insure that both ends of the filament will undergo a similar frequency and amplitude of vibration, and will oscillate substantially in phase, when the lamp is subjected to physical shocks.

In accordance with the invention, both of the leadingin wires of an incandescent lamp of the type referred to are extended equally beyond the filament, the ends of the extended portions being located and anchored in a tubular chamber formed in the bulb at the top thereof, said chamber being in the form of a cylinder or a truncated cone and the diameter of the cylinder or of the orifice of the truncated cone being less than the greatest spacing between the leading-in wires in the bulb.

It is important, in order to prevent or to minimize the damage to the filament by vibration and shocks, that both ends of the filament are subjected to a similar frequency and amplitude of vibration and that they oscillate substantially in phase. In accordance with my invention, both lead wires are symmetrically disposed about the filament and equally extended, with their free ends sprung into the tubular or substantially cylindrical chamber formed in the bulb, in axial alignment with the axis of the lamp. In order that the extended leading-in wires can be sprung into the tubular chamber and thereby yieldably maintained apart therein to prevent their contacting one another so as to short-circuit the filament, the diameter of the chamber opening should be less than the greatest spacing between the leading-in wires in the bulb.

Further objects and features of my invention will appear from the following detailed description of species thereof and from the accompanying drawings which illustrate the invention as applied to a miniature lamp such as used for bicycle or hand flashlight lamps.

In the drawing,

Fig. 1 is an elevation of an electric incandescent lamp comprising my invention; and

Fig. 2 is a fragmentary elevation of a modified lamp construction according to the invention.

Referring to Fig. l, the glass bulb 1 is provided with a chamber 2 of cylindrical configuration, formed at the top of the bulb and having its axis in line with the axis of the bulb. A pair of leading-in wires '3, cut to predetermined lengths, are sealed into the neck end of the bulb 1 in a suitable manner, such as by the well-known butt-seal method, and they extend into the bulb in the general direction of the axis thereof in spaced-apart relation, they being held in such spaced-apart relation by means of a bead 4 of glass or other insulating material. From the glass support head 4 the leading-in wires 3 extend into the bulb 1 in diverging relation, and a concentrated filament 5, such as a coiled or coiled-coil tungsten wire, is suitably connected across the leading-in wires 3 at a predetermined position between the head 4 and the free ends 6 of the leading-in wires. The lengths of the leading-in wires in the bulb are such that, when the filament 5 is in its correct position in the bulb with respect to a base 7 cemented or otherwise suitably secured to the neck end of the bulb, the portions of the leadingin wires beyond the filament joints are of sutficient length to enable them to extend and be sprung into the chamber 2 so as to yieldingly press against the side wall thereof, whereby the filament is located and held in its correct position. The diameter of the cylindrical chamber 2 should be less than the greatest spacing between the leading-in wires 3 within the bulb, but care must be taken to ensure that the chamber 2 is large enough to enable the ends 6 of the leading-in wires to be kept apart so as not to contact one another when positioned in the chamber 2 and thus cause the short-circuiting of the filament.

In Fig. 2, the chamber 2' is shown in the form of a truncated cone, the angle of the sides of the cone substantially conforming with the angle between the two converging ends 6 of the leading-in wires when sprung into place in the chamber 2'. In this embodiment also, care must be taken that the innermost ends 6 of the two leading-in wires 3 within the chamber 2' are kept well apart so as not to contact one another.

My invention permits an accurate location of the filament, with reference to the axis of the base 7 and to the appropriate light center, to be achieved by the engagement of the leading-in wires 3 with the wall of the chamber 2 or 2, without any optical focusing at sealing or basing of the lamp. Moreover, the free ends 6 of the leading-in wires 3 can be housed in the chamber 2 or 2 without any disturbing forces acting on the ends, so that during operation the filament is held in position at all times and any vibration imparted thereto will be of the same frequency throughout its whole length, and the amplitude of vibration of the filament ends will be substantially the same and in phase.

It will be obvious that slight modifications can be made to the shape of the chamber 2 or 2 without departing from the spirit of my invention. For instance, if desired, the top of the chamber, instead of being fiat as shown can be concave or convex.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric incandescent lamp comprising a bulb having a small outward tubular chamber at the top end thereof, a pair of leading-in wires of substantially identical character and shape sealed in the other end of said bulb and extending thereinto in a common plane toward the top end thereof, and a coiled filament extending across and disposed substantially in the said plane of said leading-in wires and electrically connected thereto at corresponding points along their length, both of said leading-in wires having extended portions extending into and yieldingly pressing outwardly against the side wall of said chamber, the opening of said chamber being less than the greatest spacing of the leading-in wires in the bulb but sufiiciently large to accommodate both of said extended leading-in wire portions therein without touching under normal use of the lamp, and the said extended portions of said leading-in wires being of predetermined lengths and thereby locating said concentrated filament in a definite predetermined position in said bulb.

2. An electric incandescent lamp of the character set forth in claim 1 wherein the said chamber is of cylindrical shape.

References Cited in the file of this patent UNITED STATES PATENTS 406,498 Backstrom July 9, 1889 988,308 Campbell Apr. 4, 1911 1,983,362 Geiger et al. Dec. 4, 1934 2,132,368 Geiger Oct. 4, 1938 

